Buggy code:
board . addGameObject ( new Door ( ) , 13 , 1 ) ; board . createWallVertical ( 0 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) - 1 ) , 0 ) ; board . createWallVertical ( 0 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) - 1 ) , LevelLoader . MAX_BOARD_WIDTH ) ; board . createWallCorners ( 0 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT ) ; board . createWallHorizontal ( 0 , LevelLoader . MAX_BOARD_WIDTH , LevelLoader . MAX_BOARD_HEIGHT ) ; board . createWallVertical ( 0 , 3 , 7 ) ; board . createWallVertical ( ( ( LevelLoader . MAX_BOARD_HEIGHT ) - 2 ) , LevelLoader . MAX_BOARD_HEIGHT , 7 ) ; board . addGameObject ( new Door ( true , 2 ) , 8 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) - 3 ) ) ; board . createWallHorizontal ( 9 , LevelLoader . MAX_BOARD_WIDTH , ( ( LevelLoader . MAX_BOARD_HEIGHT ) - 3 ) ) ; board . createWallVertical ( 0 , 2 , 13 ) ; board . createWallCorners ( 13 , LevelLoader . MAX_BOARD_WIDTH , 0 , 3 ) ; board . createWallCorners ( 7 , LevelLoader . MAX_BOARD_WIDTH , ( ( LevelLoader . MAX_BOARD_HEIGHT ) - 3 ) , LevelLoader . MAX_BOARD_HEIGHT ) ; board . createWallHorizontal ( 13 , LevelLoader . MAX_BOARD_WIDTH , 3 ) ; createCantineTables ( 1 , 1 , 1 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) - 1 ) ) ; createCantineTables ( 6 , 6 , 1 , 5 ) ; createCantineTables ( 6 , 6 , 9 , 11 ) ; break ; case LevelLoader . SECOND_FLOOR_1 : if ( model . getBoss ( "Ruud" ) . getAlive ( ) ) { board . addGameObject ( model . getBoss ( "Ruud" ) , ( ( LevelLoader . MAX_BOARD_WIDTH ) - 3 ) , 1 ) ; } createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; board . createWallHorizontal ( 10 , 14 , 0 ) ; placeKey ( 19 , 6 , 2 ) ; createRightClassRoom ( ) ; break ; case LevelLoader . SECOND_FLOOR_2 : createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( true , 1 ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; placeKey ( 20 , 4 , 4 ) ; createRightClassRoom ( ) ; break ; case LevelLoader . SECOND_FLOOR_3 : if ( spawnArea . equals ( "Elevator" ) ) { board . addGameObject ( avatar , 9 , 2 ) ; } board . addGameObject ( new Elevator ( ) , 8 , 1 ) ; board . addGameObject ( new Elevator ( ) , 9 , 1 ) ; createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( true , 2 ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; placeKey ( 17 , 8 , 5 ) ; createRightClassRoom ( ) ; break ; case LevelLoader . SECOND_FLOOR_4 : createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( true , 3 ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; board . createWallHorizontal ( 10 , 14 , LevelLoader . MAX_BOARD_HEIGHT ) ; placeKey ( 19 , 6 , 6 ) ; createRightClassRoom ( ) ; break ; case LevelLoader . THIRD_FLOOR_1 : createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( true , 3 ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; board . createWallHorizontal ( 0 , LevelLoader . MAX_BOARD_WIDTH , 0 ) ; <START_BUG> placeKey ( 10 , 14 , 7 ) ; <END_BUG> createRightClassRoom ( ) ; break ; case LevelLoader . THIRD_FLOOR_2 : createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( true , 3 ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; createRightClassRoom ( ) ; break ; case LevelLoader . THIRD_FLOOR_3 : if ( spawnArea . equals ( "Elevator" ) ) { board . addGameObject ( avatar , 9 , 2 ) ; } board . addGameObject ( new Elevator ( ) , 8 , 1 ) ; board . addGameObject ( new Elevator ( ) , 9 , 1 ) ; createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( true , 3 ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; createRightClassRoom ( ) ; break ; case LevelLoader . THIRD_FLOOR_4 : if ( model . getBoss ( "Evert" ) . getAlive ( ) ) { board . addGameObject ( model . getBoss ( "Evert" ) , ( ( LevelLoader . MAX_BOARD_WIDTH ) - 3 ) , 1 ) ; } createBasicLevel ( 14 , LevelLoader . MAX_BOARD_WIDTH , 0 , LevelLoader . MAX_BOARD_HEIGHT , new Door ( true , 3 ) , 14 , ( ( LevelLoader . MAX_BOARD_HEIGHT ) // 2 ) ) ; board . createWallHorizontal ( 10 , 14 , LevelLoader . MAX_BOARD_HEIGHT ) ; createRightClassRoom ( ) ; break ; case LevelLoader . FOURTH_FLOOR_1 : if ( model . getBoss ( "Jan" ) . getAlive ( ) ) { board . addGameObject ( model . getBoss ( "Jan" ) , ( ( LevelLoader . MAX_BOARD_WIDTH ) - 1 ) , 5 ) ; } board . createWallHorizontal ( 1 , ( ( LevelLoader . MAX_BOARD_WIDTH ) - 1 ) , 0 ) ;

Fix:
placeKey ( 10 , 10 , 7 ) ;